usb: ehci: add Faraday USB 2.0 EHCI support

This patch adds support to both Faraday FUSBH200 and FOTG210,
the differences between Faraday EHCI and standard EHCI are
listed bellow:

1. The PORTSC starts at 0x30 instead of 0x44.
2. The CONFIGFLAG(0x40) is not only un-implemented, and
   also has its address space removed.
3. Faraday EHCI is a TDI design, but it doesn't
   compatible with the general TDI implementation
   found at both U-Boot and Linux.
4. The ISOC descriptors differ from standard EHCI in
   several ways. But since U-boot doesn't support ISOC,
   we don't have to worry about that.

Signed-off-by: Kuo-Jung Su <dantesu@faraday-tech.com>
CC: Marek Vasut <marex@denx.de>